#include<bits/stdc++.h>
using namespace std;
long long n,a[1000100],dp[1000100],minn=-1e18,ans;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	minn = a[1];
	for(int i=1;i<=n;i++){
		if(a[i]<minn){
			minn = a[i];
			dp[i] = dp[i-1];
		}else{
			dp[i] = max(dp[i-1],a[i]-minn);
		}
		ans = max(ans,dp[i]);
	}
	cout<<ans;
	return 0;
}

86pts，minn的值已经按照别的警示帖改了，但还是#12 #13 WA